1. Field of the Invention
The present invention relates to an MPLS (Multi-Protocol Label Switching)-based multicast routing protocol, more particularly, to a point-to-multipoint traffic routing method that routes a multicast traffic through a determined tree on an MPLS network.
2. Description of the Related Art
An MPLS ensures quality of service (QoS) for a traffic transported through an IP (Internet Protocol) network and efficient use of network resources. Therefore, it is spotlighted in traffic engineering field.
The MPLS traffic engineering determines an LSP (Label Switched Path) in various ways to appropriately accept a variety of QoS demands for users' IP packets. The LSP is a point-to-point (PTP) path connecting from an ingress to an egress edge router.
By the way, due to rapid growth of an IP base network, various multimedia services such as VoIP, VOD, AOD, on-line movie, and video conference are being demanded. Many of those multi-media services require a point-to-multipoint (PTM) tree. If a PTM multimedia service is provided through PTP LSPs, use efficiency of network resources becomes worse and/or management of QoS becomes not easy. This is because multicast traffic is routed through a unicast way.
In the Internet proposal room of the IETF committee, many ways to distribute MPLS label are being listed up. Those many ways use PIM-SM or PIM-DM which is conventional multicast IP protocol. Besides the proposed many ways, MPLS multicasting way is being standardized in the IETF.
However, since tree determining methods of existing multicast protocols proposed until now are all receiver-based, it is not easy to reflect intentions of a service provider or users appropriately. As a result, network resources can not be used efficiently, which results in deterioration of service quality.
To resolve such problems, new traffic path determining methods, which determine traffic paths at an originating node on an MPLS network, have been proposed by this applicant. They have been filed at Korean Intellectual Property Office in Patent Application No. 2001-65798, No. 2001-65799, and No. 2001-65800, respectively on Oct. 24, 2001 altogether.